1. Field of the Invention
The present invention relates to detectors, specifically to a detector for use in a vehicle for measuring the relative speed and distance of objects in the path of travel of the vehicle.
2. Description of the Related Art
As the world's population continues to grow, more and more traffic congestion occurs on roadways, particularly in urban areas. With more cars on the road, it becomes more difficult for an individual driver to avoid a collision, particularly when following other vehicles too closely.
In the prior art, efforts have been made to increase the safety of a driver by providing devices for installation in or on a vehicle, which measure the distance to an object in front of the vehicle, and which also measure the closing speed of the object relative to the vehicle. Such devices may be used to warn a driver when the distance between his vehicle and the vehicle in front of him is closing quickly, making a collision likely if corrective action is not implemented.
Devices intended for use in vehicles, which measure distance, speed or both for the purposes stated herein-above, are known in the prior art. U.S. Pat. No. 3,984,836 to Oishi et al. discloses a device which measures the distance to an object in a vehicle's path using microwave radar technology. Microwave pulses are transmitted from a transmitting antenna in a direction forward of the vehicle on which the antenna is mounted. The microwaves are reflected off of the object, then received by a microwave receiver. The device calculates the distance from the vehicle to the object based on the time delay between the transmission and the reception of the microwave pulses. The distance is displayed in a relative fashion on a light display next to the vehicle's speedometer.
U.S. Pat. No. 4,003,049 to Sterzer et al. discloses a system using frequency-modulated continuous-wave radar to determine the distance to an object in a vehicle's path. The system uses transmitting and receiving antennas, and computes distance by measuring the frequency shift between the transmitted and the received signals. No particular audible or visual system for providing the distance information to the driver is disclosed.
U.S. Pat. No. 4,072,945 to Katsumata et al. disloses a radar-operated collision avoidance system which measures both distance from a vehicle to an object in the vehicle's path, and relative speed of the object. The system utilizes these measured quantities, as well as other conditions such as human factors, road and weather conditions to determine whether the vehicle is approaching the object at an unsafe speed. No particular audible or visual system for providing the distance information to the driver is disclosed.
U.S. Pat. No. 5,314,037 to Shaw et al. discloses a system using lasers to determine the distance to an object in a vehicle's path, and the speed of the object relative to the vehicle. The system divides the speed into the distance to calculate a time period until collision. The system also calculates a plurality of minimum allowable times to establish various safety levels. For example, a disastrous level minimal allowable time would be shorter than a critical level minimal allowable time, which would be shorter than a warning level minimal allowable time. Each level can be associated with a different degree of audible or visual alarm. No specific embodiments of audible or visual alarm are disclosed.